When messages are stored in large memory areas (such as memory cards or a large memory in a mobile device) it is very common for users to have hundreds of messages in their inbox. It is very tiresome to find old messages or sort for those that are wanted and those that can be discarded. With the tremendous popularity growth in SMS (short message service), MMS (multimedia-messaging service) and shared inbox with e-mail, the number of messages the user wants to keep grows very rapidly in today's world of intense communications. Storing and sorting these messages on currently available devices, especially portable communication devices with severe size and weight restrictions, is difficult and represents a significant challenge.
In a data warehousing/mining world, large amounts of data are stored into multi-dimensional databases that support many views into the data, organized into hierarchies. It is certainly overkill to create a multi-dimensional database for the scale of storage of messages in the portable communication devices such as mobile electronic devices and mobile phones but similar approaches can be used to optimize views and searches along pre-defined hierarchies.